1. Field Of The Invention
The present invention relates to systems in which an output signal is to be produced, which is to be either analog or digital in nature, and which is to be created as a selectable nonlinear function of an input signal that may be either analog or digital in nature. In particular, this invention applies to systems in which electronic means are to be used to transform an input into a desired output signal that is a selectable nonlinear function of the input signal, as opposed to systems in which mechanical means are to be used for said purpose.
Significant advantages offered by this invention are in the speed at which the nonlinear output signal can be changed, and the ease with which the nonlinear function can be changed.
Moreover, in some embodiments of this invention, there exists the capability to change the nonlinear function while the system is in operation, or to change the nonlinear function even though the mechanical portion of the system may be in what would normally be considered to be a hazardous environment.
2. State Of The Art And Background Of This Invention
There are existent in technologies today numerous applications in which: a capability to implement a specific nonlinear relationship between input data (an input signal), supplied in either analog or digital form, and an analog output signal is required; as well as other applications in which a capability to implement a specific nonlinear relationship between input data, in analog form, and a digital output signal is required.
In a number of these applications, a motor may be mechanically coupled to an object in such a way that motion of the moving member of the motor causes motion of said object, and a machine tool is required to cut into the object to a depth that varies in a prescribed manner over the range of displacement, either angular or rectilinear, of said object. In such arrangements, the nonlinear relationship may be implemented by means of one or more mechanical cams moved either directly or indirectly by the motor.
It is, however, frequently difficult, if not impossible, for a human being to change the nonlinear function implemented in the set of mechanical cams after the system has been installed and put into operation. Thus, in radioactive areas or areas of intense heat, and other similar hazard-to-health environments, for example, the surroundings are so dangerous to human life that the presence of a human being to effect a change in the nonlinear relationship is frequently not practical, if it is indeed at all possible.
In yet other applications, it may be difficult for a human being to implement a change in the nonlinear relationship, between input and output, because of the speed at which it is desired that the change be effected. The changing of jobs being performed in an automated manufacturing plant is one example of an application in which such a problem is encountered.
A further consideration is cost. In many applications, the cost of the mechanical cams themselves, and, in particular, the labor cost of changing mechanical cams when a change in the nonlinear relationship between the input data and the output data is desired, is very substantial. An inexpensive means for implementing and changing the input-output relationship is, therefore, to be desired and is provided by this invention.
Still another advantage of this invention is the speed at which the input may be allowed to change. In existing systems, in which an analog signal is sampled periodically, either by its own internal clock or by a digital computer, the maximum rate at which the analog input may change is limited by the sampling rate available. Because the minimum time interval between samples in such systems is of the order of a microsecond or larger (often approximately one hundred microseconds), the maximum allowable rate of change of the analog input is fairly low. The present invention virtually eliminates the foregoing speed-of-change limitation, because no sampling is required if the analog-to-digital conversion is performed, for example, by an optical shaft encoder.
In many applications, a potentiometer may be used to convert an angular displacement of a rotating shaft to a voltage that varies in a desired manner with said angular displacement. When a different variation of voltage with angular displacement is desired, a potentiometer with a different taper must be designed and manufactured. The cost and effort and time delay incurred in making a change in taper can be very greatly reduced by employing the features of this invention, which provides an electronic potentiometer with an easily changeable taper.